#define  _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>

int main()
{
    float arr[5] = { 0 };
    for (int i = 0; i < 5; i++)
    {
        scanf("%f ", &arr[i]);
    }
    printf("%.2f", (arr[0] + arr[1] + arr[2] + arr[3] + arr[4]) / 5);

    return 0;
}